1. Non-Electronic Hearing Aids
Non-electronic hearing aids have been around for many years and their development has traditionally preceded electronic hearing aids. Unfortunately, the cost of purchasing and repairing today's electronic hearing aids has become quite substantial. In fact, today's electronic hearing aids may easily cost upwards of $2000 each. For a typical user, this cost is frequently doubled as users often wear hearing aids in both ears. The cost of these expensive electronic hearing aids is often not covered by medical insurance or Medicare. In addition, electronic hearing aids require a continual supply of new batteries. As a result, a need exists for an effective inexpensive acoustic or non-electronic hearing aid manufactured without the need for any internal expensive electrical componentry.
Many different forms of acoustic hearing aids have been developed, both pre-dating and concurrent with the development of electronic hearing aids. All of these non-electronic hearing aids can, however, typically be conveniently analyzed as belonging to one or the other of the following two separate families of hearing aids.
A first family of non-electronic hearing aids consists of a large outwardly-protruding cup or scoop for capturing and focusing sound waves into a user's ear canal. An early development of such a device is found in U.S. Pat. No. 656,182 to Ehrhardt. This device consists of two hollow truncated cones or scoops which each fit around the user's ears. The novel aspect of this invention was that it could be conveniently attached to the user's head by use of a head band, so as to avoid the necessity of being held by the hand, as was the case for pre-existing ear trumpets.
U.S. Pat. No. 1,708,257 to Campbell also disclosed a sound wave catcher which physically contacts the back of the user's ear and conducts sound waves into the user's ears. As such, the operation of this device resembles the use of the hand being cupped behind and outside of the ear. A novel aspect of this invention was that the sound wave catcher could be folded so as to be carried in a vest pocket or other small space.
U.S. Pat. No. 2,537,201 to Amfitheatrof disclosed a pair of cupped-shaped sound collectors which fit behind the user's ears and are connected together by a head band passing over the user's head. The novel aspect of this invention was that the sound cups or baffles could be selectively regulated by extending them such that the surface area of the overall sound gathering cup could be varied.
U.S. Pat. No. 3,938,616 to Brownfield disclosed a sound multiplier comprised of a pair of thin cups mounted on a person's head which are held in position by a head band such that these cups fits sealingly about a person's ear. The cups are separated from the sides of the wearer's head by a layer of felt. These cups have a spiral contour opening which is approximately co-incident with the front face of the user.
U.S. Pat. No. 4,574,912 to Fuss, et al. disclosed an earmuff hearing aid consisting of a pair of thin-shelled outwardly-extending ear extenders transversely in contact with the listener's head behind the user's ears. These extenders were held in position by a head band. Having these extenders positioned behind the ears and in contact with the listener's head, sounds were thereby amplified and transmitted directly into the user's ears.
U.S. Design Pat. No. 292,916 to Ikeda shows an ornamental design for a scoop-type non-electronic sound amplifier.
U.S. Pat. No. 4,771,859 to Breland disclosed a hearing aid apparatus consisting of two cupped-shaped members with sound reflective surfaces which direct sound waves into the user's ears. Also disclosed in this design is the modified embodiment of the invention using a foam padding in a rear portion of the cupped-shaped members to cause a gentle forward bending of the user's ears to further increase hearing ability.
U.S. Pat. No. 4,997,056 to Riley discloses an ear-focused acoustic reflector. This device mechanically intercepts frontally-generated sound waves in a manner that accurately preserves their phase coherency at all frequencies, and then reflects these sounds into the ear canals of the listener. To accomplish this, the Riley device uses a pair of acoustic reflectors which are parabolically shaped and are held in position by a head band passing over the user's head. The Riley device further uses acoustically damping material which operates to prevent the amplifying of sound vibrations emanating from sources not directly in front of the user. Accordingly, the Riley device allows the user to actively select the sound source to be amplified, while blocking out unwanted sounds. Specifically, sounds coming from other sources are not amplified as an acoustic dampening pad is provided on the reflectors such that any unwanted vibrations intercepting the reflectors are not transmitted by bone conduction into the ears. Accordingly, the object of the Riley device is to increase the degree of acoustic fidelity which a listener hears emanating from an audio system's loud speaker by providing a very directionally selective system which operates to shield the listener from sounds emitted from other sources.
The disadvantages of this first family of hearing aids are numerous. First, they all are rather large in size. Using large outwardly-scooped cup or parabolic-shaped sound reflectors, this family of hearing aids consumes considerable space. Secondly, these devices tend to be quite wide, spanning a large distance between their lateral ends and the user's ears. These two disadvantages combine to produce a third disadvantage, namely that the device is not aesthetically appealing to a typical user.
A second family of acoustical hearing aid devices operate on the principle of inserting a thin tubular-shaped member directly into the user's ear canal while concurrently covering this region with a second external member having a small opening such that this external member encloses a small cavity of air while covering the first internal member.
A first example is found in U.S. Pat. No. Re. 20,871 to Donoher which discloses a simple auricle having a wig hair covering placed thereover.
U.S. Pat. No. 1,453,969 to Brown discloses a second example of an auricle device. This device operates to intensify sound wave vibration reflected into the ear canal and the external member of this device engages the side of the head to transmit vibrations into the bones of the skull.
U.S. Pat. No. 4,556,122 to Goode discloses a similar device. This device modifies the normal concha resonance and combines it with the ear canal resonance to shift the normal sound pressure gain of 15 to 20 decibels at the tympanic membrane downward from 2,600 to 3,000 kilohertz to 1,500 to 2,000 kilohertz. A 5-15 dB increase in sound pressure is generated in the 1000-2500 Hz range. To achieve this, the Goode device provides a thin hollow shell that fits snugly into the auricle and concha of the external ear so as to enclose a volume of air within the concha. An opening in the shell lets sound waves into this air volume. The proper ratio of this air volume to the area of the opening in the shell controls the peak frequency of amplification desired, the amplitude and also the bandwidth of amplification. Accordingly, the Goode device is able to provide significant sound amplification for persons with mild high frequency hearing loss. By varying the volume of this chamber and the area of the opening within a certain range, the resonance frequency of the device can be adjusted to meet the specific hearing amplification needs of a particular individual suffering from mild hearing loss.
A first disadvantage with this second family of hearing aids is that they are limited over the range of frequencies with which they selectively operate. Furthermore, using a device such as the Goode device, the desired frequencies over which this device is to operate must be pre-set for each particular user. This pre-setting is done by modifying the structure of the device itself. Once this modification has been made, the device can not be re-modified for another range of frequencies. This second family of hearing aids is also limited by the fact that it employs an invasive internal member which is typically tubular in shape and fits into the user's ear canal. A less intrusive device, avoiding this feature, would instead be much more desirable. Operating on the principle of selectively vibrating at certain resonance frequencies, this second family of devices does not truly catch, funnel or reflect a broad spectrum of sound waves, concentrating these sound waves in the user's ears as was accomplished by the first family of hearing aids. Therefore, a third disadvantage of this second family of hearing aids is that sound vibrations are transmitted directly into the ear canal regardless of the direction from which the sounds are emanating. Accordingly, any directional selectivity enabling the user to choose to listen to one particular sound source is reduced, impaired or non-existent in the second family of non-electronic hearing aids. This presents problems for some hearing-impaired persons who have trouble distinguishing between various sound sources.
Lastly, an anechoic ear piece which can not be easily classified into either of the above two families of devices exists as found in U.S. Pat. No. 4,890,688 to Baker. This anechoic ear piece does not operate to amplify sounds and is therefore only marginally related to the present invention. Instead, this device is simply designed to block out the reception of all sound waves approaching the ears with the sole exception of sound waves emanating from a source directly in front of the listener, preferably being the sound waves coming from a stereo speaker.
In light of the existing prior art and its associated limitations, a long-felt need exists for a hearing aid device which would combine the positive features of the first and second families of non-electronic hearing aids while overcoming the limitations of both these families. Specifically, a need exists for a device which is able to gather and reflect into the ear more sound waves than would otherwise normally be received by the ear in the absence of such a device. These sound waves should be collected and directed into the ear canals using a device which does not require the large, wide sound reflectors as seen in the first family of prior art hearing aids. In addition, this new device should operate well over a wide range of frequencies, be directionally selective, not require non-reversible structural modifications or adjustments be made for each user, and not require invasive tubular members be inserted into the inner ear, thus overcoming the problems inherent in the above second family of non-electronic hearing aids. Accordingly, the preferred device should not entail sound collectors extending too far beyond the sides of the ear and should be able to effectively gather and reflect sound waves into the ear canal over a wide variety of frequencies. This device should also have the added advantage of transmitting sound waves directly into the ears through conduction in the skull bones of the user. Furthermore, this device should be directionally selective such that the user may, simply by orienting his or her head towards a particular source of emitted sound waves, amplify particular sounds as desired.
2. Objects of the Invention
It is an object of the present invention to provide an acoustical hearing aid device which employs no electrical or electronic circuit components.
It is a further object of the present invention to provide a versatile acoustic hearing aid which is very inexpensive.
It is a further object of the present invention to provide an acoustical hearing aid which does not have a cosmetically or aesthetically objectionable large size or laterally extending width. This device should also be lightweight.
It is a further object of the present invention to provide an acoustical hearing aid which gathers and reflects sound waves into a user's ear canals over a wide range of frequencies.
It is a further object of the present invention to provide a non-electronic hearing aid which does not require a tubular member be inserted into the user's ear canal.
It is a further object of the present invention to provide an acoustic hearing aid offering a gain in volume of approximately 25 decibels in the 1,500 kilohertz range.
It is a further object of the present invention to provide an acoustical hearing aid which is directionally selective such that the user can choose to amplify the sound waves emitted from a particular source or direction simply by reorienting his or her head.
It is a further object of the present invention to provide an acoustic hearing aid which does not require any permanent structural modifications to be made for each individual user.
It is a further object of the present invention to provide an acoustic hearing aid which is durable, reliable and easy to fabricate and which has no repair costs.
It is a further object of the present invention to provide an acoustical hearing aid which is lightweight, comfortable and easy to use.